This invention relates in general to fluid filters and more particularly to an improved construction for a filter medium and seal for filters of the type having removable filter elements and cleanable or replaceable filter media.
Fluid filters, including filters for liquids and gases, are in widespread use. It is desirable in such filters to provide a filter medium that is supported and sealed in use in a manner which substantially eliminates leaks without reducing the efficiency of the filter. In the past, providing a substantially leak-free seal for removable filter media has been difficult. Where attempts have been made to glue gasket seals onto the remainder of the filter medium, some leakage has occurred through gaps in the adhesive. Additionally, where gasket seals have been glued onto the rest of the filter element, the glue has deteriorated under certain pH conditions and temperature changes, causing leakage. Further, where gaskets are utilized, the gaskets can deform and shrink under pressure, particularly when a high pressure differential exists across the filter medium, allowing contaminant by-pass.
It has been another problem with prior filter medium and seal constructions that the methods used for forming a leak-proof seal have tended to reduce the efficiency of the filter. Where such filters have utilized a gasket under pressure, the force necessary to create a leak-proof seal to the gasket has, due to the construction of the filters, caused deformation and fatigue of the filter-medium supporting frame and reduced the efficiency of the filters. Further, where a neck has been utilized to form a surface to which the filter medium can be clamped, up to three (3) inches in length of the filter and up to 25% of the filter surface area have been lost in order to provide space for the neck.
Exemplary prior art filters are shown in U.S. Pat. Nos. 1,218,848; 2,420,414; 3,486,626; 3,633,753; 3,633,757 and 4,615,803. Additional prior art constructions are illustrated in the accompanying drawings.
It is a feature of this invention to provide a fluid filter medium that eliminates potential leakage paths that were present in many prior art filters.
It is another feature of this invention to provide a fluid filter medium that can operate at higher fluid pressures, and at greater pressure differentials across the filter medium, than prior art filters.
It is still another feature of this invention to provide a fluid filter medium that will increase the filter surface area and efficiency of the filter over some prior art filters by avoiding the requirement of a neck to clamp the filter medium.